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Chemistry Around UsPlasticsPlastics are used for thousands of different objectsPlastics are used for thousands of different objects The most common types of plasticsThe most common types of plasticsPolythene (PE) 聚乙烯The most common types of plasticsPolypropene (PP) 聚丙烯The most common types of plasticsPolyvinyl chloride (PVC) 聚氯乙烯The most common types of plasticsPolystyrene (PS) 聚苯乙烯The most common types of plasticspolyterafluoroethene (PTFE) or teflon 聚四氟乙烯The most common types of plasticsNylon 尼龙The most common types of plasticsUrea-methanal 脲甲醛The most common types of plasticsPerspex 有机玻璃The most common types of plasticsMalamine 三聚氰酰胺1. The classification of plasticsTwo simple tests for classification:The first test --- heating a sample of the plastics in boiling water or in the oil.The second test --- heating a sample of the plastics strongly.Two simple tests for classificationTest 1Test 2The wall socket chars and cracks when heated stronglyPlastics can be classified into two main types according to their thermal behaviorThermoplastics ( 热塑性塑料 )Examples: polythene (PE) 聚乙烯 polypropene (PP) 聚丙烯 polyvinyl chloride (PVC) 聚氯乙烯 polystyrene (PS) 聚苯乙烯 perspex 有机玻璃 nylon 尼龙 Thermosetting plastics （热固性塑料） Examples: urea-methanal 脲甲醛 melamine 三聚氰酰胺--- They are flexible. They soften and melt on heating and re-harden on cooling.--- They are hard and rigid. They do not soften or melt but decompose on strong heating.bakelite 电木2. The formation of plasticsn→monomerpolymerethenepolyethene→vinyl chloridepolyvinyl chloriden2. The formation of plasticsPolymer （聚合物） --- very long molecules （分子）Monomer （单体） --- smaller moleculesPolymerization （聚合反应） --- the joining...